Passenger screening system and method

ABSTRACT

A method and scanner configured to determine whether a person&#39;s feet are positioned at a predetermined location of a predetermined scanning area and configured to scan the feet to detect a presence of a metal, an explosive, or other type of target substance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims benefit under 35U.S.C. §120 or 121, to prior-filed, co-pending U.S. non-provisionalpatent application Ser. No. 11/456,748, filed on Jul. 11, 2006, which ishereby incorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

Not Applicable

REFERENCE TO A SEQUENCE LISTING, A TABLE, OR COMPUTER PROGRAM LISTINGAPPENDIX SUBMITTED ON COMPACT DISC

Not Applicable

BACKGROUND OF THE INVENTION

This invention relates generally to personnel screening systems utilizedat passenger terminals, and more particularly, to a system configured toimprove passenger handling in a transportation terminal and a method ofoperating the same.

The Transportation Security Administration (TSA) has recently mandatedmore stringent inspection procedures be implemented by the travelindustry to reduce the possibility of passengers boarding a carrier suchas a plane, for example, carrying concealed weapons, explosives, orother contraband. To facilitate preventing passengers boarding a planecarrying concealed weapons, explosives, etc., the TSA requires that allpassengers be screened prior to boarding the aircraft.

For example, passengers arriving at the airport terminal first submit toa manual verification process that generally includes presenting theirboarding pass and a form of identification such as a driver's license orpassport, for example, to security personnel. The security personnelthen manually verify that the passenger has a valid boarding pass, thename on the identification corresponds to the name on the boarding pass,and that the picture on the license or passport corresponds to thepassenger presenting the license and boarding pass to the securitypersonnel. After the manual verification process is completed, thepassenger is requested to walk through a metal detector to ensure thatthe passenger is not carrying any concealed weapons.

While the current passenger screening process is reliable, the processmay require additional security personnel to perform the screeningprocedures. As a result, the cost of implementing an effective securityscreening process at a transportation terminal is increased. Moreover,the time required to perform the screening process is increased thusnecessitating passengers to arrive relatively early to allow thepassenger sufficient time to complete the screening process.

BRIEF SUMMARY OF THE INVENTION

In one aspect, a method of operating a passenger screening kiosk systemto perform at least one verify a passenger's identity, detect thepresence of an explosive material, and detect the presence of a metallicmaterial is provided. The method includes initiating a prompt to beissued by the passenger screening kiosk system to prompt the passengerto enter the passenger screening kiosk system, prompting the passengerto enter the passenger screening kiosk system, and determining whetherthe passenger is within the passenger screening kiosk system.

In another aspect, a passenger screening kiosk system is provided. Thesystem includes an identity verification system, a metal detectionsystem, an explosives detection system, and a computer coupled to theidentity verification system, the metal detection system, and theexplosives detection system. The computer is configured to prompt apassenger to enter the passenger screening kiosk system, and determinewhether the passenger is within the passenger screening kiosk system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a right perspective view of an exemplary kiosk system;

FIG. 2 is a front view of the kiosk system shown in FIG. 1;

FIG. 3 is a side section view of the kiosk system shown in FIG. 1;

FIG. 4 is a simplified block diagram of an exemplary kiosk securitysystem that includes a first modality and a second modality;

FIG. 5 is a schematic illustration of an exemplary Quadrupole Resonance(QR) screening system that may be utilized with the kiosk shown in FIGS.1-4;

FIG. 6 is a right perspective view of the kiosk shown in FIGS. 1-3including the screening system shown in FIG. 5;

FIG. 7 is a schematic illustration of a portion of the screening systemshown in FIG. 6;

FIG. 8 is a schematic illustration of a portion of the screening systemshown in FIG. 6;

FIG. 9 is a flowchart illustrating an exemplary method of operating thescreening system shown in FIGS. 1-8;

FIG. 10 is a front view of the kiosk shown in FIGS. 1-8 including anexemplary system that may be utilized to determine the passenger's feetposition within the kiosk;

FIG. 11 is a front view of the kiosk shown in FIGS. 1-8 includinganother exemplary system that may be utilized to determine thepassenger's feet position within the kiosk;

FIG. 12 is a front view of the kiosk shown in FIGS. 1-8 includinganother exemplary system that may be utilized to determine thepassenger's feet position within the kiosk;

FIG. 13 is a front view of the kiosk shown in FIGS. 1-8 includinganother exemplary system that may be utilized to determine thepassenger's feet position within the kiosk.

FIG. 14 is a schematic illustration of the system shown in FIG. 13during a second mode of operation;

FIG. 15 is a front view of the kiosk shown in FIGS. 1-8 includinganother exemplary system that may be utilized to determine thepassenger's feet position within the kiosk;

FIG. 16 is a first screen shot generated utilizing the system shown inFIGS. 1-8; and

FIG. 17 is a second screen shot generated utilizing the system shown inFIGS. 1-8.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a right perspective view of an exemplary passenger screeningsystem 10. FIG. 2 is a front view of the passenger screening systemshown in FIG. 1, FIG. 3 is a side section view of the passengerscreening system 10 shown in FIG. 1, and FIG. 4 is a simplifiedschematic illustration of the passenger screening system 10. As shown inFIG. 4, and in the exemplary embodiment, system 10 includes at least afirst modality 12 referred to herein as passenger identificationverification system 12, a second modality 14 referred to herein aspassenger screening system 14, and a third modality 16 referred toherein as a metal detection system 16. System 10 also includes at leastone computer 18, and a communications bus 20 that is coupled betweenmodalities 12, 14, and 16, and computer 18 to enable operator commandsto be sent to at least one of modalities 12, 14, and 16 and to allowoutputs generated by modalities 12, 14, and 16 to be delivered tocomputer 18 and thus utilized by computer 18 for data analysis orutilized by an operator of computer 18. In one embodiment, modalities12, 14, and 16 are hardwired to computer 18. In another embodiment,communications bus 20 is a local area network. Optionally,communications bus 20 includes an internet connection.

Modalities 12, 14, and 16 are integrated into a single screening system10. In the exemplary embodiment, modalities 12, 14, and 16, and computer18 are each housed within a single kiosk or housing 22. Optionally,computer 18 is housed separately from kiosk 22 and electrically coupledto modalities 12, 14, and 16 utilizing bus 20. As used herein, a kioskis defined as a relatively small area that is at least partiallyenclosed by at least one wall. In the exemplary embodiment, the kioskincludes a third, or forward wall, that is coupled between the pair ofwalls to at least partially enclose the passenger screening area.

Referring again to FIGS. 1-3, kiosk 22 includes a first wall 24, asecond wall 26 that is positioned substantially parallel to first wall24, and a third wall 28 that is positioned substantially perpendicularto and coupled between first and second walls 24 and 26, respectively.Kiosk 22 also includes a floor 30 extending between first, second, andthird walls 24, 26, and 28, that, in one exemplary embodiment, includesan inductive sensor unit 32 that is described in further detail below.For example, and as shown in FIGS. 1 and 2, the three walls, 24, 26, and28 define a single opening such that a passenger may enter and exitkiosk 22 through the same opening. Optionally, kiosk 22 may include twowalls 24 and 26 such that the passenger may enter kiosk 22 through afirst opening, traverse through kiosk 22, and exit kiosk 22 through asecond opening.

In one embodiment, the kiosk walls each have a height 34 of betweenapproximately 28-42 inches. The embodiments of FIGS. 1, 2, and 3 showthe left and right walls 24 and 26 formed with an approximate arcuateshape having a radius which approximates the height of the walls. Notethat walls 24 and 26 have been optionally truncated at the entrance.Truncating walls 24 and 26 facilitates the movement of people into andout of system 10, and further extends the notion of openness of thescreening system. Optionally, kiosk walls 24 and 26 have a height 34that is greater than a height of a typical passenger, i.e. like a phonebooth for example, such that the entire passenger's body may bescreened.

In the exemplary embodiment, kiosk 22 also includes a control panelsection 36 that is coupled to forward wall 28 and extends upwardly fromforward wall 28 to a predetermined height to facilitate providingvarious operator controls. Control panel section 36 also includes amonitoring or display device 38 that may be utilized to prompt apassenger to either input selected information into the screening systemand/or prompt a passenger to perform various actions within thescreening system to facilitate the system to expediently verify theidentity of the passenger and inspect the passenger for contraband aswill be discussed later herein.

In the exemplary embodiment, to facilitate verifying a passenger'sidentity, system 10 includes a electronic card reader 42 wherein apassenger enters a registration card into a receptacle provided withkiosk 22. In the exemplary embodiment, the passenger registration cardincludes biometric information of the passenger that has been encodedonto the registration card obtained by the passenger during aprescreening process. For example, a passenger may obtain a registrationcard by registering with the Registered Traveler Program wherein apassenger is pre-screened by the TSA or some other authorized screeningentity, to obtain biometric information that is then stored on thepassenger's registration card. The biometric information may include thepassengers fingerprints, iris scan information, hand print information,voice recognition information, or other suitable biometric information.The information on the registration may be encoded on a magnetic strip,use optical read codes, use an RF-read memory chip, or other embeddedmedia.

Accordingly, during operation, the passenger inserts their registrationcard into electronic card reader 42. Passenger identity verificationsystem 12 then prompts the passenger to position a selected body part ona sensor that is utilized to collect biometric information from thepassenger within kiosk 22. The collected information is then compared tothe biometric information stored on the registration card to verify theidentity of the passenger.

In one exemplary embodiment, passenger identity verification system 12may be implemented utilizing a iris scan device 44 to generate biometricinformation that is then compared to the information on the RegisteredTraveler's registration card in order to verify that the passenger beingscreened is the passenger to whom the card in fact belongs. In theexemplary embodiment, iris scan device 44 includes an illuminatingdevice 46 that directs light having desired characteristics to the eyeunder observation such that at least one of the iris and/or pupil of theeye under observation take a characteristic shape. The exemplary irisscan device 44 also includes a light imaging apparatus 48 to generate animage of the iris and/or pupil. The generated image is then compared toinformation that is stored on the registration card. It should berealized that in the exemplary embodiment, the generated image describedherein are computer generated images or data files of an image that arestored within the computer and not physical images. Specifically, thesystems described herein generate an electronic image or datafile thatis compared to an electronic image or datafile stored on theregistration card or optionally within system 10 to verify the identityof the passenger.

In another exemplary embodiment, passenger identity verification system12 may be implemented utilizing a fingerprint scan device 50 wherein apassenger places a finger on the fingerprint scan device 50 such thatthe device obtains an image of the fingerprint of the passenger beingverified. The generated image is then compared to information that isstored on the registration card or optionally, information stored oncomputer 18. It should be realized that in the exemplary embodiment, thegenerated image described herein are computer generated images or datafiles of an image that are stored within the computer and not physicalimages. Specifically, the system described herein generate an electronicimage or datafile that is compared to an electronic image or datafilestored on the registration card or optionally within system 10 to verifythe identity of the passenger. Optionally, the passenger identityverification system 12 may be implemented utilizing a hand scanningdevice, a facial image recognition system and/or a voice recognitionsystem in order to verify the identity of the passenger.

As discussed above, passenger identity verification systems 12 generallyrequires a passenger to be prescreened in order to generate theinformation that is stored within computer 18. For example, passengersmay participate in the government's Registered Traveler Program wherebyan initial, relatively thorough, screening of the passenger is conductedto generate information about the passenger that may be utilized bysystem 10 at a later date. As such, the passenger may choose to have afingerprint scan completed, an iris scan, a hand scan, a voice scan,and/or a facial recognition scan completed. The information collectedduring the prescreen procedure is then stored within or provided tosystem 10, e.g. via a card reader reading a registration card, such thatwhen a passenger enters kiosk 22, the verified information may becompared to the information presented by the passenger within kiosk 22to facilitate reducing the amount of time to complete passengerscreening and thus improve the convenience of passenger screening.Moreover, prescreening facilitates shifting limited security resourcesfrom lower-risk passengers to passengers that have not be prescreened.

In the exemplary embodiment, passenger screening system 14 may beimplemented using a quadrupole resonance (QR) detection system thatutilizes quadrupole resonance to detect explosives such as, but notlimited to C4, Semtex, Detasheet, TNT, ANFO, and/or HMX since thequadrupole resonance signature of these explosives is unique andmeasurable in seconds.

Nuclear Quadrupole Resonance (NQR) is a branch of radio frequencyspectroscopy that exploits the inherent electrical properties of atomicnuclei and may therefore be utilized to detect a wide variety ofpotentially explosive materials. For example, nuclei havingnon-spherical electric charge distributions possess electric quadrupolemoments. Quadrupole resonance arises from the interaction of the nuclearquadrupole moment of the nucleus with the local applied electrical fieldgradients produced by the surrounding atomic environment. Any chemicalelement's nucleus which has a spin quantum number greater than one halfcan exhibit quadrupole resonance. Such quadrupolar nuclei include: ⁷Li,⁹Be, ¹⁴N, ¹⁷O, ²³Na, ²⁷Al, ³⁵Cl, ³⁷Cl, ³⁹K, ⁵⁵Mn, ⁷⁵As, ⁷⁹Br, ⁸¹Br,¹²⁷I, ¹⁹⁷Au, and ²⁰⁹Bi. Many substances containing such nuclei,approximately 10,000, have been identified that exhibit quadrupoleresonance.

It so happens that some of these quadrupolar nuclei are present inexplosive and narcotic materials, among them being ¹⁴N, ¹⁷O, ²³Na, ³⁵Cl,³⁷Cl, and ³⁹K. The most studied quadrupolar nucleus for explosives andnarcotics detection is nitrogen. In solid materials, electrons andatomic nuclei produce electric field gradients. These gradients modifythe energy levels of any quadrupolar nuclei, and hence theircharacteristic transition frequencies. Measurements of these frequenciesor relaxation time constants, or both, can indicate not only whichnuclei are present but also their chemical environment, or,equivalently, the chemical substance of which they are part.

When an atomic quadrupolar nucleus is within an electric field gradient,variations in the local field associated with the field gradient affectdifferent parts of the nucleus in different ways. The combined forces ofthese fields cause the quadrupole to experience a torque, which causesit to precess about the electric field gradient. Precessional motiongenerates an oscillating nuclear magnetic moment. An externally appliedradio frequency (RF) magnetic field in phase with the quadrupole'sprecessional frequency can tip the orientation of the nucleusmomentarily. The energy levels are briefly not in equilibrium, andimmediately begin to return to equilibrium. As the nuclei return, theyproduce an RF signal, known as the free induction decay (FID). A pick-upcoil detects the signal, which is subsequently amplified by a sensitivereceiver to measure its characteristics.

FIG. 5 is a simplified schematic illustration of an exemplary quadrupoleresonance system 14 that includes a radio frequency source 62, a pulseprogrammer and RF gate 64 and an RF power amplifier 66 that areconfigured to generate a plurality of radio frequency pulses having apredetermined frequency to be applied to a coil such as sensor 32 (alsoshown in FIGS. 1-3). A communications network 70 conveys the radiofrequency pulses from radio frequency source 62, pulse programmer and RFgate 64 and RF power amplifier 66 to sensor 32 that, in the exemplaryembodiment, is positioned within kiosk 22. The communications network 70also conducts the signal to a receiver/RF detector 72 from sensor 32after the passenger is irradiated with the radio frequency pulses.

FIG. 6 is a right perspective view of kiosk 22 including quadrupoleresonance (QR) detection system. As stated above, quadrupole resonance(QR) detection system 14 includes an inductive sensor 32 that in theexemplary embodiment, is positioned proximate third wall 28approximately between first and second walls 24 and 26. In accordancewith this embodiment, inductive sensor 32 may be positioned within arecessed region 80 of floor 30, between an entrance ramp 82 and thirdwall 28. This recessed region 80 may also be referred to as the sensorhousing. In FIG. 6, the inductive sensor 32 has been omitted to showsensor housing 80, which is recessed within floor 30.

As shown in FIG. 6, and in the exemplary embodiment, inductive sensor 32may be implemented using two anti-symmetric current branches 90 and 92that may be located on opposing sides of a medial plane 94.Specifically, current branch 90 is positioned on one side of medialplane 94, while current branch 92 is positioned on the opposite side ofmedial plane 94.

Inductive sensor 32 may be configured in such a manner that both currentbranches 90 and 92 experience current flow that is generally orsubstantially parallel to the left and right walls 24 and 26. Forexample, the current branches 90 and 92 may be placed in communicationwith an electrical source (not shown in this figure). During operation,current flows through current branch 90 in one direction, while currentflows through current branch 92 in substantially the opposite direction.The term “anti-symmetric current flow” may be used to refer to thecondition in which current flows through the current branches insubstantially opposite directions.

In the exemplary embodiment, inductive sensor 32 is implemented using aquadrupole resonance (QR) sensor. For convenience only, variousembodiments will be described with reference to the inductive sensorimplemented as a QR sensor 32, but such description is equallyapplicable to other types of inductive sensors.

In the exemplary embodiment, current branches 90 and 92 collectivelydefine a QR sheet coil that is shown as sensor 32 in FIG. 7. Forconvenience only, further discussion of the QR sensor will primarilyreference a “QR sheet coil,” or simply a “QR coil”. During a typicalscreening process, a passenger enters the system at an entrance 96, andthen stands within an screening region defined by QR sensor 32.Specifically, the passenger may stand with their left feet positionedrelative to current branch 90 and their right feet positioned relativeto current branch 92. The QR sensor then performs a screening processusing nuclear quadrupole resonance (NQR) to detect the presence of atarget substance associated with the passenger.

As shown in FIG. 5, QR sensor 32 is in communication with the RFsubsystem, defined generally herein to include radio frequency source62, pulse programmer and RF gate 64, and RF power amplifier 66 whichprovides electrical excitation signals to current branches 90 and 92.The RF subsystem may utilize a variable frequency RF source to provideRF excitation signals at a frequency generally corresponding to apredetermined, characteristic NQR frequency of a target substance.During the screening process, the RF excitation signals generated by theRF source may be introduced to the specimen, which may include theshoes, socks, and clothing present on the lower extremities of apassenger standing or otherwise positioned relative to the QR sensor 32.In the exemplary embodiment, the QR coil 32 also functions as a pickupcoil for NQR signals generated by the specimen, thus providing an NQRoutput signal which may be sampled to determine the presence of a targetsubstance, such as an explosive, utilizing computer 18, for example.

In the exemplary embodiment, QR sensor 32 utilizes an EMI/RFI(electromagnetic interference/radio frequency interference) shield tofacilitate shielding sensor 32 from external noise, interference and/orto facilitate inhibiting RFI from escaping from the screening systemduring an screening process. In the exemplary embodiment, walls 24, 26,and 28 are configured to perform RF shielding for QR sensor 32.Specifically, walls 24, 26, and 28 are electrically connected to eachother, to entrance ramp 82, and to sensor housing 80 to form an RFshield 100.

Each of the shielding components, i.e. walls 24, 26, and 28 may befabricated from a suitably conductive material such as aluminum orcopper. Typically, the floor components, i.e. ramp 82 and sensor housing80 are welded together to form a unitary structure. Additionally, walls24, 26, and 28 may also be welded to the floor components, or securedusing suitable fasteners such as bolts, rivets, and/or pins. QR sensor32 may be secured within sensor housing 80 using, for example, any ofthe just-mentioned fastening techniques. If desired, walls 24, 26, and28, entrance ramp 82, and the QR sensor 32 may be covered withnon-conductive materials such as wood, plastic, fabric, fiberglass, andthe like.

FIG. 7 is a simplified schematic illustration of the exemplary QR sensor32 shown in FIG. 6. Left current branch 90 is shown having upper andlower conductive elements 110 and 112, which are separated by anon-conductive region. Similarly, right current branch 92 includes upperand lower conductive elements 114 and 116, which are also separated by anon-conductive region. The left and right current branches 90 and 92collectively define the QR coil of sensor 32, and may be formed from anysuitably conductive materials such as copper or aluminum, for example.

No particular length or width for the current branches 90 and 92 isrequired. In general, each current branch may be dimensioned so that itis slightly larger than the object or specimen being inspected.Generally, current branches 90 and 92 are sized such that a passenger'sleft feet and right feet (with or without shoes) may be respectivelyplaced in close proximity to the left and right current branches 90 and92. This may be accomplished by the passenger standing over the left andright current branches. In this scenario, the left and right branchesmay each have a width of about 4-8 inches and a length of about 12-24inches. It is to be understood that the terms “left” and “right” aremerely used for expositive convenience and are not definitive ofparticular sides of the structure.

Upper and lower conductive elements 110 and 112 are shown electricallycoupled by fixed-valued resonance capacitor 118 and tuning capacitor120, which is a switched capacitor that is used to vary tuningcapacitance. Upper and lower conductive elements 114 and 116 may besimilarly configured.

FIG. 7 also includes several arrows which show the direction of currentflow through the left and right current branches 90 and 92 which in theexemplary embodiment, is in a counter-clockwise direction. Duringoperation, current flows through left current branch 90 in onedirection, while current flows through right current branch 92 insubstantially the opposite direction. The reason that current flowsthrough the two current branches in opposite directions is because theleft and right current branches 90 and 92 each have a differentarrangement of positive and negative conductive elements. For instance,left current branch 90 includes a positive upper conductive element 110and a negative lower conductive element 112. In contrast, right currentbranch 92 includes a negative upper conductive element 114 and apositive lower conductive element 116. This arrangement is one exampleof a QR sensor providing counter-directed or anti-symmetric current flowthrough the current branches.

In accordance with the exemplary embodiment, current flows between theleft and right current branches 90 and 92 during operation since thesecomponents are electrically coupled via ramp 82 and the sensor housing80. During operation, a passenger may place their left feet over leftcurrent branch 90 and their right feet over right current branch 92. Insuch a scenario, current is directed oppositely through each branchresulting in current flowing from toe to heel along left current branch90, and from heel to toe along right current branch 92. In the exemplaryembodiment, QR sensor 32 is positioned within sensor housing 80 to forma non-conductive gap between current branches of the QR sensor. This gapallows the magnetic fields to circulate about their respective currentbranches.

In contrast to conventional inductive sensor systems, thecounter-directed magnetic fields generated by QR sensor 32 arewell-attenuated and have a topography that is especially suited for usewith a kiosk that includes a first wall 24, a second wall 26 that isopposite to first wall 24, and a third wall 28 that is substantiallyperpendicular to first and second walls 24 and 26, and a floor 30 thatis connected to first wall 24, second wall 26, and third wall 28.

As an example of a practical application, the left and right currentbranches 90 and 92 may be positioned about 2-7 inches from respectivewalls 24, 26, and 28 using a plurality of non-conductive regions. Inaddition, current branches 90 and 92 may be positioned about 4-14 inchesfrom each other using a non-conductive region.

Passenger screening system 14 may also be implemented using a fingertiptrace explosive detection system 210 (shown in FIGS. 1 and 2). Fingertiptrace explosive detection system 210 is capable of detecting minuteparticles of interest such as traces of narcotics, explosives, and othercontraband on the passenger's finger or hand for example. In theexemplary embodiment, detection system 210 is located proximate to aboarding pass scanner (not shown) such that as the passenger scans theboarding pass, at least a portion of the passenger's hand approximatelysimultaneously passes over fingertip trace explosive detection system.Optionally, the passenger is prompted to press a button to activatefingertip trace explosive detection system 210 such that trace materialson the finger surface are collected and then analyzed by fingertip traceexplosive detection system 210. As such, fingertip trace explosivedetection system 10 is configured to determine when a passenger's fingerhas been placed over the device to activate the fingertip traceexplosive screening procedure.

In the exemplary embodiment, fingertip trace explosive detection system210 includes an ion trap mobility spectrometer (not shown) that isutilized to determine whether any substantially minute particles ofinterest such as traces of narcotics, explosives, and other contrabandis found on the passenger's finger. For example, the ion trap mobilityspectrometer is preferentially useful in identifying trace explosives orother contraband on a passenger's finger that may be indicative of thepassenger recently manipulating explosives or other contraband and assuch does not require imaging or localization.

In the exemplary embodiment, and referring again to FIGS. 1 and 2,modality 16, i.e. the metal detection system 16 may be implementedutilizing a pair metal detection coils 130 that are utilized inconjunction with inductive sensor 32. Each of the metal detection coils130 may be configured to detect conductive objects present within thevicinity of the lower extremities of the inspected passenger. Thesesignals may be communicated to a suitable computing device for examplecomputer 18. More specifically, and as shown in FIG. 6, modality 16includes a first metal detection coil 132 and a second metal detectioncoil 134 that are each mounted to a side of kiosk 22.

Specifically, first metal detection coil 132 is mounted to an innersurface of first wall 24 and second metal detection coil 134 is mountedto an inner surface of second wall 26. In the exemplary embodiment,metal detection coils 132 and 134 are each mounted at a height abovefloor 30 to is most advantageous to conduct a metal detection screeningof the lower extremities of the passenger. For example, coils 132 and134 may be positioned approximately 12-40 inches above floor 30. In theexemplary embodiment, metal detection coils 132 and 134 are inductivecoils such that when a first current flows through the first metaldetection coil 132 in a first direction a first magnetic field isformed, and when the current flows through the second metal detectioncoil, in a second opposite direction, a second magnetic field is formed.

FIG. 8 is a simplified schematic illustration of the metal detectioncoils 132 and 134 shown in FIG. 6. Coil 132 and coil 134 are eachseparated by a non-conductive region 136 which generally is the utilizedfor the passenger, i.e. the passenger is positioned between coils 132and 134 to facilitate operation of the system. Coils 132 and 134 may beformed from any suitably conductive materials such as copper oraluminum, for example, and no particular length or width for the coils132 and 134 is required. In general, each coil is dimensioned so that itis slightly larger than the object or specimen being inspected. It is tobe understood that the terms “left” and “right” are merely used forexpositive convenience and are not definitive of particular sides of thestructure.

FIG. 8 also includes several arrows which show the direction of currentflow through the left and right coils 132 and 134 which in the exemplaryembodiment, is in a clockwise direction through coil 132 and in acounterclockwise direction through coil 134 such that there is no mutualinductance between the inductive sensor 32 (shown in FIG. 7) the coilpair 130 and 132. Although, an exemplary metal detection coil 130 isdescribed herein, it should be realized that a wide variety of coilstypes may be utilized.

More specifically, current is supplied to coils 132 and 134 utilizing aline driver circuit or a signal driver, for example, such that each coil132 and 134 generates a magnetic field around each respective coil. Inthe exemplary embodiment, the QR sensors 32 are utilized to monitor ordetect any changes in the magnetic field generated by coils 132 and 134.More specifically, when no metallic object is positioned between coils132 and 134, the coils are substantially balanced. That is, a balancedor null signal is injected into the QR sensors 32 such that QR sensors32 do not detect any imbalance between coils 132 and 134. However, if apassenger, carrying a metallic object is positioned between coils 132and 134, the signals generated by coils 132 and 134 will becomeunbalanced, i.e. a signal having some amplitude, will be detected by QRsensor 32. Accordingly, when system 10 is configured to operate modality14, i.e. the metal detection modality, QR sensors 32 areelectromagnetically the QR driver circuit to enable the QR sensors 32 todetect any disturbances in the magnetic field generated by coils 132 and134.

In the exemplary, embodiment, metal detection coils 132 and 134 are eachcalibrated to ensure that they are substantially in balance, i.e.produce a magnetic field of similar strength, when no metallic object ispositioned between them. Moreover, QR sensor 32 is calibrated toidentify and changes in the magnetic field generated by coils 132 and134. As such, and in the exemplary embodiment, QR sensor 32 is utilizedto detect any changes in the magnetic fields generated by coils 132 and134. In the exemplary embodiment, when the QR sensors detects a changein the magnetic fields generated by coils 132 and 134 has exceeded apredetermined threshold, an alarm or other indication will be enabled toprompt an operator that a metallic object has been detected and further,more detailed screening of the passenger may be required.

Although the exemplary metal detection system 16 described herein isgenerally is directed toward scanning the lower region of the passengerwhile the passenger is still wearing shoes, it should be realized thatsystem 16 may be implemented to scan the entire passenger with orwithout the passenger wearing shoes.

FIG. 9 is a flow diagram of an exemplary method 200 of operatingscreening system 10 to verify the identity of a passenger and detect thepresence of at least one of an explosive material and a metallicmaterial. Method 200 includes prompting 202 the passenger to enter thepassenger screening kiosk, and determining 204 whether the passenger iswithin the passenger screening kiosk system.

As discussed above, to optimize the identification and screeningoperation of system 10, the passenger being inspected should bepositioned within system 10 such that the passenger's feet arepositioned within a predetermined screening area the provides the mostoptimal screening conditions for both the first and second screeningmodalities. However, as discussed above, the passenger to be screened isgenerally unaware of the most optimal screening area. As a result,system 10 also includes a means that may be utilized to determine thatthe passenger's feet are within the predetermined area.

More specifically, the volume of space interrogated by the QR coils andthe metal detection system is finite, and as such, a means 220 isprovided to ensure that the passenger's feet remain within theinterrogation volume, i.e. the predetermined screening area, throughoutthe scan period. Moreover, the metallic detection system 16 generallyrelies on the similarity of metallic parts in shoes and on the presenceof a weapon spoiling the symmetry of the metal distribution between thetwo feet. As such, to optimize the performance of system 10, the twofeet should be placed nearly symmetrically over the QR coils and betweenthe metal detection coils in order that misplacement not generate afalse asymmetry alarm. To accomplish this, system 10 includes at leastone additional system or means 220 that is utilized to determine theplacement of each feet within the inspection system 10.

FIG. 10 is a front view of screening system 10 including a means 220that may be utilized to determine whether the passenger's feet arepositioned within a predetermined screening area within system 10. Inthis exemplary embodiment, means 220 may be implemented utilizing aninfrared imaging system 230 that includes a first infrared sensor array230 that includes a plurality of sensors 232 wherein each infraredsensor includes an infrared transmitter 234 and an infrared receiver 236that are each utilized to determine the distance between at least one ofthe passenger's feet and the infrared sensor array 230. Specifically,and in the exemplary embodiment, the sensor array 230 is fabricated suchan infrared transmitter 234 is mounted proximate to a respectiveinfrared receiver 236 and facing the same direction, such that when anobject, such as the passenger being screened, is positioned in the pathof the transmitter 234, the infrared beam is be reflected from thepassenger being screened back to the receiver 236. In the exemplaryembodiment, the receiver 236 generates a voltage output that isproportional to the distance to the object that is reflecting the beam.

In the exemplary embodiment, system 230 includes a first sensor array240 that is positioned on wall 24 and directed inwardly toward thescreening area defined between walls 24 and 26, and a second sensorarray 242 that is positioned on wall 26 and directed inwardly toward thescreening area, i.e. toward the first sensor array 240, and a thirdsensor array 244 that is positioned on wall 28. In the exemplaryembodiment, sensors 232 are each spaced linearly such that the sensors232 are approximately parallel to floor 30. Additionally, the sensors232 within each sensor array 240 and 242, respectively are spacedapproximately one inch apart, and the arrays are fabricated to include apredetermined length 246 that is equivalent to or slightly larger than apredetermined feet size of an average passenger to be screened.

During operation of system 230, when a feet are placed near eachrespective sensor array 240, 242, and 244, each respective sensor 232generates a distance measurement between the part of the side of thefeet that is in line with that respective sensor 132. Specifically, eachsensor array utilizes an angulation technique to determine the distancebetween each respective feet and the sensor arrays. This information isthen utilized to generate a distance profile of the portion of thepassengers feet that is proximate to each respective sensor array 240,242, and 244. As a result, the distance profile will substantially matcha profile of the passenger's feet being screened. Utilizing the distanceprofile generated by each respective sensor array 240, 242, and 244, acomputer, such as computer 18 for example, determines at least one ofthe length of the feet, the distance from the feet to each respectivesensor array 240, 242, and 244, the position of the feet along eachrespective sensor array 240, 242, and 244, and the angle of the feetwith respect to each respective sensor array 240, 242, and 244.Moreover, the distance profile may also be utilized to estimate thewidth of the feet from the determined feet length. Although, the term“feet” is utilized throughout the description, it should be realizedthat the term feet generally refers to the passenger's feet and thefeetwear worn by the passenger during the screening process.

The distance profile is then utilized to calculate the region of thefloor 30 that is covered by the feet. The calculated region is thencompared to the acceptable feet placement region, i.e. the predeterminedscreening area, to determine whether the passenger's feet are properlywithin the predetermined screening area. If the feet are within theacceptable region, then modality 12 is initiated to perform anexplosives screening of the passenger. Optionally, if the feet are notwithin the acceptable region, the passenger is prompted to repositioneither one or both feet. System 230 is then activated to generate anadditional distance profile as discussed above. This process iscompleted until both feet are positioned within the predeterminedscreening area and the explosive scan is completed. In the exemplaryembodiment, the passenger may be prompted to reposition one or both feetutilizing either an audio or visual indicator, generated and displayedon computer 18, for example. In the exemplary embodiment, system 230 mayinclude additional sensors 232 that are mounted proximate to, orslightly above floor 30 to facilitate the detection of narrow highheeled shoes and thus improve the screening process.

FIG. 11 is a front view of screening system 10 including an exemplarysystem 250 that may be utilized to determine whether the passenger'sfeet are positioned within a predetermined screening area within system10. In this exemplary embodiment, means 220 is implemented utilizing amachine vision system 250 that includes a first camera 252. a secondcamera 254, a third camera 256, and a fourth camera 258. In theexemplary embodiment, first and second cameras 252 and 254, are mountedproximate to the left wall 24 such that the first camera 252 ispositioned to image the forward part of the passenger's left feet, andthe second camera 254 is positioned to image the rearward, or heelportion, of the left passenger's feet. Additionally, third and fourthcameras 256 and 258, are mounted proximate to the right wall 26 suchthat the third camera 256 is positioned to image the forward part of thepassenger's right feet, and the fourth camera 258 is positioned to imagethe rearward, or heel portion, of the passenger's right feet.

In operation, utilizing two cameras to image both the left and rightfeet facilitates generating a three-dimensional image of the feetregion. More specifically, the three-dimensional representation may notbe a physical representation, rather in the exemplary embodiment,computer 18 utilizes the images generated by each camera to analyze, inthree dimensions, the proper placement of each feet within thepredetermined screening area. If system 250 determines that both feetare properly positioned within the predetermined screening area, atleast one of an explosive scan or a metal detection scan is completed.

As such, system 250 facilitates utilizing two cameras to view aparticular feature of the respective feet or shoe region to determine athree-dimensional position of that feature. Accordingly, cameras 252,254, 256, and 258 facilitate determining when each feet are in thecorrect position in the plane of the floor also determine whether thefeet or shoe is being lifted off the floor. In the exemplary embodiment,computer 18 utilizes and image processing algorithm to determine theshoe type which enables or alerts security personal of potential problemshoe types which may not be suitable for this type of explosive scan.

FIG. 12 is a front view of screening system 10 including an exemplarysystem 260 that may be utilized to determine whether the passenger'sfeet are positioned within a predetermined screening area within system10. In this exemplary embodiment, means 220 is implemented utilizing apressure responsive system 260 that includes a pair of pressure switches262 that are mounted within floor 30. In the exemplary embodiment, afirst and a second pressure switch are each mounted in or proximate tofloor 30 such that the pair of pressure switches 262 are activated bythe passenger being screened when the passenger's feet are eachpositioned within the predetermined screening area such that at leastone of an explosive scan or a metal detection scan may be completed.

FIG. 13 is a front view of screening system 10 including an exemplarysystem 300 that may be utilized to determine whether the passenger'sfeet are positioned within a predetermined screening area within system10. FIG. 14 is a schematic illustration of the exemplary system 300shown in FIG. 13. In this exemplary embodiment, means 220 is implementedutilizing an ultrasonic ranging system 300 that includes a transmitter302 that drives transducer elements 304 within a probe 306 to emitpulsed ultrasonic signals toward the passenger being screened. A varietyof geometries may be used. The ultrasonic signals are back-scatteredfrom structures within the body or preferably from metallic or explosiveobjects concealed on the passenger, to produce echoes that return totransducer elements 304. The echoes are received by a receiver 308. Auser input device, such as computer 18 for example, may be used tocontrol operation of ultrasonic ranging system 300 and to process theacquired ultrasound information.

During operation of system 300, when a feet are placed near eachrespective probe 306, the transmitter 302 is activated to emitultrasonic radiation toward the passenger being screened. The reflectedor backscattered radiation is detected by each respective receiver 308and computer 18 is utilized to generate a distance measurement betweenthe part of the side of the feet that is in line with that respectiveprobe 306. Specifically, the round trip time interval from theultrasonic wave is emitted and received by probe 306 is calculated foreach respective probe 306. This information is then utilized to generatea distance profile of the portion of the passenger's feet that isproximate to each respective probe 306. As a result, the distanceprofile will substantially match a profile of the passenger's feet beingscreened. The distance profile is then utilized by system 10 asdescribed above to determine the proper position of the passenger's feetwithin system 10.

FIG. 15 is a front view of screening system 10 including an exemplarysystem 320 that may be utilized to determine whether the passenger'sfeet are positioned within a predetermined screening area within system10. In this exemplary embodiment, means 220 is implemented utilizing arastered laser ranging system 320 that includes a plurality of laseremitters 322 each having a respective light receiving device 324. In theexemplary embodiment, the rastered laser imaging system 320 ispositioned and utilized similar to system 300 discussed previouslyherein.

Described herein is a kiosk that is configured to optimize passengerhandling into and out of the passenger screening kiosk 22, and moreover,to control the actions of the passenger within the kiosk to facilitatereducing the time required to perform passenger identification and thevarious screening for both metal detection and explosives and/orcontraband detection.

As such, the kiosk includes a modality utilized to perform explosivesand or drug detection, a second modality that is utilized to performmetal detection, a third modality that is utilized to verify theidentity of the passenger within the kiosk, and a means to ensure thatthat the passenger's feet are positioned properly within the kiosk tofacilitate improving the accuracy of the first and second screeningmodalities.

Specifically, the kiosk discussed herein is utilized to enhancepassenger movement through a screening portion of a travel terminal,such as for example, an airport terminal. To accomplish this, apassenger is prompted to enter kiosk 22. In one embodiment, kiosk 22 isconfigured to generate an indication that the kiosk is available toperform screening, for example, computer 18 may generate a visual“ENTER” indication that may be viewed by the passenger on display 38.Optionally, local security personnel may prompt a passenger to enterkiosk 22. As such, kiosk 22 includes a sensor that is utilized todetermine when a passenger has entered kiosk 22. For example, in oneembodiment, system 10 is configured to automatically determine when apassenger has entered kiosk 22 utilizing a pressure sensor installedwithin floor 30 or a photodetector 390 (shown in FIG. 17), for example.As such, when a passenger has entered kiosk 22, the photodetector 390 orpressure sensor will activate to provide computer 18 an indication thata passenger is within kiosk 22.

After system 10 has determined that a passenger to be inspected iswithin kiosk 22, system 10 may then prompts the passenger to enteridentity information. For example, as discussed above, kiosk 22 mayrequest that a passenger enter a registration card having thepassenger's previously verified biometric information into theelectronic card reader 42. System 10 then automatically prompts thepassenger to place a body part onto one of the identity verificationsystems. For example, system 10 may prompt the passenger to place atleast one eye in front of the iris scan device 44. System 10 thendetermines whether the passenger's eye is positioned in front of theiris scan device 44 and automatically initiates scanning the passenger'seye to produce an image of the iris as discussed above. The generatedimage is then compared to the biometric information stored on thepassenger's registration card to verify the identity of the passenger.

In another embodiment, system 10 automatically prompts the passenger toplace a finger on the fingerprint scan device 50. System 10 thendetermines whether the passenger's finger is positioned on thefingerprint scan device 50 and automatically initiates scanning thepassenger's finger to produce an image of the iris as discussed above.The generated image is then compared to the biometric information storedon the passenger's registration card to verify the identity of thepassenger.

After the identity of the passenger has been determined, system 10 thenprompts a passenger to perform an explosives detection search. Forexample, system 10 may prompt the passenger to press their thumb on thefingertip trace explosive detection system 210. In the exemplaryembodiment, system 210 is configured to determined whether thepassenger's finger is positioned on system 21- and automaticallyinitiate a trace explosives scan on the fingertip of the passengerwithin kiosk 22 in a relatively short time period, thus decreasing thetime required to inspect a passenger for explosives.

To facilitate performing either a metal scan or an explosives scanningprocedure of the lower leg and feet region of the passenger, system 10is configured to automatically prompt the passenger to correctlyposition their feet within kiosk 22.

Specifically, system 10 first prompts the passenger to position theirfeet within the predetermined scanning area as discussed above. System10 then determines the relative location of a passenger's feet withinthe screening system to verify that the passenger's feet are positionedwithin the predetermined screening area. In the exemplary embodiment,the position of the passenger's feet within kiosk 22 is determinedutilizing means 220 described above.

For example, FIG. 16 illustrates a first screen shot generated utilizingthe system shown in FIGS. 1-8, and FIG. 17 is a second screen shotgenerated utilizing the system shown in FIGS. 1-8. As shown in FIG. 16,a passenger being inspected is positioned incorrectly within thescreening area. Specifically, neither feet are positioned within thepredetermined screening area, roughly outlined by the feet shapedoutlines 400. As a result, means 220 will not initiate either a metaldetection or explosive scan to screen the passenger. System 10 may thenprompt the passenger to reposition their feet correctly within system10.

As shown in FIG. 17, means 220 has determined that passenger beinginspected is positioned correctly within the screening area.Specifically, both feet are positioned within the predeterminedscreening area, roughly outlined by the feet shaped outlines 400. As aresult, system 10 automatically initiates a metal detection and/orexplosive scan to screen the passenger. Although, FIGS. 16 and 17illustrate exemplary locations, illustrated as feet on the floor of thekiosk. It should be realized that in the exemplary embodiment, kiosk 22does not include any visual indications installed on the floor of thekiosk to assist the passenger in properly aligning their feet to performthe inspection, rather kiosk 22 prompts the passenger utilizing thecomputer screen or an audio command to reposition their feet, asdiscussed above. However, in an optional embodiment, visual prompts maybe installed on the floor of the kiosk to assist the passenger.

The screening system described herein is configured to automaticallyprompt a passenger to enter identity information and compare the enteredinformation to information stored on a passenger's registration card.The screening system then prompts the passenger to position a body parton an identity verification apparatus, such as an iris scan device or afingerprint scan device. System 10 then determines when the passenger'sbody part is positioned on the identity verification apparatus andperforms a scan. System 10 is also configured to prompt a person toposition portions of the body, such as the legs and feet for example, ina predetermined position to optimized both metal detection scanning andexplosive scanning of the lower regions of the legs and feet. Afterdetermining that the passenger's body is properly positioned, system 10automatically initiates the screening process to detect both metal andexplosive materials that may be attached to the passenger's body.

Specifically, the system described herein is configured to prompt apassenger to enter the screening system, automatically determine when apassenger is within the screening system. The system then prompts thepassenger to enter information that may be utilized by the screeningsystem to verify the identity of the passenger. Once the passenger'sidentity is verified the screening system prompts the passenger toposition a body part and then determines that the body part is correctlypositioned.

The system described herein facilitates improving passenger flow througha security checkpoint within a travel terminal. Specifically, the systemautomatically prompts a passenger to be inspected to enter the system,prompts the passenger to position selected body parts in front of or onselected screening systems, determines that the body part is positionedon the screening system, and automatically initiates the screeningprocess. As such, the system described herein facilitates guiding apassenger through a screening process and thus substantially reduces theamount of time required to screen a passenger within the travelterminal. As a result, more travelers may be screened in a reducedamount of time to further improve travel efficiency. Moreover, thesystem described herein is highly reliable. As a result, the detectionof contraband and other possible dangerous devices is increased, whilereducing the overall time required to detect the same items.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

1. A method, comprising: sensing when a person's feet are placed withina predetermined screening area of a scanner; and verifying that the feetare at respective predetermined locations within the predeterminedscreening area.
 2. The method of claim 1, further comprising: scanningthe feet with a magnetic field to detect a presence of metal.
 3. Themethod of claim 2, wherein the scanner is a metal detector.
 4. Themethod of claim 1, further comprising: scanning the feet using radiofrequency spectroscopy to detect a target substance.
 5. The method ofclaim 4, wherein the scanner is a quadrupole resonance scanner.
 6. Themethod of claim 4, wherein the target substance is an explosive.
 7. Themethod of claim 1, further comprising: generating a distance profile ofthe feet when the feet are proximate a sensor array based on a signaloutput by the sensor array; and utilizing the distance profile todetermine at least one of: a length of a foot, a distance from a foot tothe sensor array, a position of a foot along the sensor array, and anangle of a foot with respect to the sensor array.
 8. The method of claim7, wherein verifying that the feet are at respective predeterminedlocations within the predetermined screening area further comprises:utilizing the distance profile to calculate a region of thepredetermined area that is covered by the foot; and comparing thecalculated region with a predetermined acceptable foot placement region.9. The method of claim 1, further comprising: outputting a prompt toreposition the feet, if the feet are determined not to be at therespective predetermined locations.
 10. The method of claim 9 whereinthe prompt is an audio indicator generated by a computer processor. 11.The method of claim 9, wherein the prompt is a visual indicatorgenerated by a computer processor.
 13. The method of claim 1, whereinthe scanner further comprises an inductive sensor, the method furthercomprising: outputting a prompt to reposition the feet symmetricallyover the inductive sensor, if the feet are determined not to be at therespective predetermined locations.
 14. The method of claim 1, whereinthe scanner further comprises two metal detection coils, the methodfurther comprising: outputting a prompt to reposition the feetsymmetrically between the two metal detection coils, if the feet aredetermined not to be at the respective predetermined locations.
 15. Themethod of claim 7, wherein the sensor array is an infrared sensor arraythat comprises an infrared transmitter and an infrared transceiver. 16.The method of claim 1, wherein the scanner further comprises a firstcamera and a second camera, the method further comprising: operating thefirst camera to generate a first image of the feet; operating the secondcamera to generate a second image of the feet; combining the first imageand the second image; and determining a position of the feet using thecombined first image and the second image.
 17. The method of claim 1,wherein the scanner further comprises a pressure sensor, the methodfurther comprising: outputting a prompt to reposition the feet toactivate the pressure sensor, if the feet are determined not to bewithin the respective predetermined locations.
 18. The method of claim1, wherein the scanner further comprises an ultrasonic ranging systemhaving an ultrasonic transmitter and an ultrasonic receiver, the methodfurther comprising: activating the ultrasonic transmitter to emit aplurality of pulsed electronic signals into at least a portion of theperson; activating the ultrasonic receiver to receive echoes from theperson; and processing the received echoes to determine whether the feetare positioned at the respective predetermined locations.
 19. The methodof claim 1, wherein the scanner further comprises a laser ranging devicehaving a light emitting device and a light receiving device, the methodfurther comprising: activating the light emitting device to emit a lightpulse for reflection from the person; activating the light receivingdevice to receive the reflected light pulse; measuring a round trip timeinterval of the light pulse; and utilizing the measured round trip timeinterval to determine whether the feet are positioned at the respectivepredetermined locations.
 20. The method of claim 1, wherein verifyingthat the feet are positioned at respective predetermined locationsfurther comprises: verifying that a first foot is positioned at a firstpredetermined location; and verifying that a second foot is positionedat second predetermined location.
 21. A scanner, comprising: a metaldetector having two metal detection coils that are spaced apart relativeto each other; an inductive sensor configured to detect a targetsubstance; a position sensor configured to sense when a person's feetare placed within a predetermined screening area of the scanner; and acomputer coupled with the metal detector, the inductive sensor, and theposition sensor, the computer configured to: operate the metal detectorto scan the feet for a presence of metal; operate the inductive sensorto scan the feet for a presence of the target substance; and operate theposition sensor to verify that the feet are positioned at respectivepredetermined locations within the predetermined screening area.
 22. Thescanner of claim 22, wherein the target substance is an explosive. 23.The scanner of claim 21, wherein the computer is further configured to:output a prompt to reposition the feet symmetrically over the inductivesensor, if the feet are determined not to be positioned at therespective predetermined locations.
 24. The scanner of claim 21, whereinthe computer is further configured to: output a prompt to reposition thefeet symmetrically between the two metal detection coils, if the feetare determined not to be positioned at the respective predeterminedlocations.
 25. The scanner of claim 21, wherein the position sensor isan infrared sensor array having an infrared transmitter and having aninfrared receiver positioned to receive an infrared signal emitted fromthe infrared transmitter.
 26. The scanner of claim 21, wherein theposition sensor comprises: a first camera configured to generate a firstimage of the feet; a second camera configured to generate a second imageof the feet; and wherein the computer is further configured to combinethe first image and the second image and to determine from the combinedimage whether the feet are positioned at the respective predeterminedlocations.
 27. The scanner of claim 26, wherein the computer is furtherconfigured to: outputting a prompt to reposition the feet, if the feetare determined not to be positioned at the respective predeterminedlocations.
 28. The scanner of claim 21, wherein the position sensor is apressure sensor configured to activate when depressed by at least one ofthe feet.
 29. The scanner of claim 28, wherein the computer is furtherconfigured to: output a prompt to reposition the feet to activate thepressure sensor, if the feet are determined not to be positioned at therespective predetermined locations.
 30. The scanner of claim 21, whereinthe position sensor comprises: an ultrasonic transmitter; and anultrasonic receiver positioned and configured to receive an ultrasonicsignal emitted by the ultrasonic transmitter.
 31. The scanner of claim30, wherein the computer is further configured to: activate theultrasonic transmitter to emit a plurality of pulsed ultrasonic signalsinto at least a portion of the person; activate the ultrasonic receiverto receive echoes from the person; and determine from the receivedechoes whether the feet are positioned at the respective predeterminedlocations.
 32. The system of claim 21, wherein the position sensorcomprises a laser ranging device having a light emitting device and alight receiving device, wherein the computer is further configured to:activate the light emitting device to emit a light pulse for reflectionfrom the person; activate the light receiving device to receive thereflected light pulse; measure a round trip time interval of the lightpulse; and utilize the measured round trip time interval to determinewhether the feet are positioned at the respective predeterminedlocations.
 33. The method of claim 21, wherein the computer is furtherconfigured to operate the position sensor to: verify that a first footis positioned at a first predetermined location; and verify that asecond foot is positioned at second predetermined location.